ΔE 14.1, fair: the same colour family, but not a straight swap. Titan Mars Pale is noticeably lighter than Eldar Flesh. They are different kinds of paint: Citadel Eldar Flesh is an opaque base/layer paint and Golden Titan Mars Pale is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Titan Mars Pale is noticeably lighter than Eldar Flesh. They are different kinds of paint.
The same difference applies the other way round: Eldar Flesh is noticeably darker.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Eldar Flesh on the colour wheel See Titan Mars Pale on the colour wheel
All matches: Eldar Flesh equivalents · Titan Mars Pale equivalents